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How often do earthquakes occur?

How often do earthquakes occur?. Once a year Once a month Once a week Once a day http://www.seed.slb.com/flash/science/features/earth/livingplanet/quake_map/en/index.htm?width=600&height=500&popup=true&terms=epicenters http://earthquake.usgs.gov/. Earthquakes. Seismology  Seismologist 

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How often do earthquakes occur?

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  1. How often do earthquakes occur? • Once a year • Once a month • Once a week • Once a day • http://www.seed.slb.com/flash/science/features/earth/livingplanet/quake_map/en/index.htm?width=600&height=500&popup=true&terms=epicenters • http://earthquake.usgs.gov/

  2. Earthquakes Seismology  Seismologist  Fault  Deformation  Elastic rebound  study of earthquakes scientist who studies earthquakes and seismic waves a break in the crust along which plates shift and slip past each other rocks changing shape due to stress from tectonic motion stress builds up to the point where the rock breaks and snaps back

  3. Epicenter– the point on the Earth’s surface directly above an Earthquake’s starting point • Focus – the point inside the Earth where the earthquake begins

  4. Seismic Wavesvibrations that are generated by the earthquake and travel through the Earth pressure waves (primary) shear waves (secondary) Surface through the entire earth only through solid on the earth’s surface slowest, but most damaging fastest slower up & down, and side to side (circle) back and forth up and down

  5. Surface wave

  6. Seismic Wave Motion with Surface Effects

  7. Seismic Wave Motion

  8. Measuring Seismic Waves • Seismograph– Instrument that record waves • Seismogram – Printout of waves created by seismograph

  9. Seismographs

  10. Predicting Earthquakes (SCEC) • http://www.youtube.com/watch?v=ixVVuN-mF1M • Italian Seismologists: • http://www.nytimes.com/2012/10/23/world/europe/italy-convicts-7-for-failure-to-warn-of-quake.html?_r=0

  11. Earthquake Strength and Intensity What is the measure of the strength of an earthquake called? Magnitude measures the strength of the ground motion • Richter scale  • Based on a factor of _____ for each level. • A magnitude 3 is ____ times as strong as a magnitude 2. • A magnitude 4 is ____ times as strong as a magnitude 3. • A magnitude 4 is _____ times as strong as a magnitude 2. 10 10 10 100 Historic Earthquakes Chile 1960 May 22 19:11:14 UTC Magnitude 9.5 The Largest Earthquake in the World

  12. Mercalli Scale • Measures Intensity – how much it is felt by people and how much damage it causes • Not as scientific because • not based on seisomogram recordings but on peoples’ observations • areas closer to epicenter will have higher intensity • damage depends on quality of construction

  13. S Waves Arrive P Waves Arrive

  14. Identify the Richter Scale Magnitude of the earthquake • Las Vegas Seismic Station • What is the S-P lag time? • What is the distance to the earthquake epicenter? • What is the S-wave amplitude? • What is the magnitude using the nonogram?

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